Fluid flow computation, visualization, and analysis

ABSTRACT

This document discusses, among other things, systems, devices and methods for fluid flow analysis for example, in an education environment. The light source, for example, a laser, is housed to illuminate particles in a fluid while minimizing exposure to the user. A control unit is provided that is remote from the fluid flow device. The fluid flow device further includes a removable fluid obstacle such that different fluid flow effects can be obtained. A computational unit is provided to perform computational fluid flow dynamics analysis on fluid flow models. The computed data can then be compared to the test data from the fluid flow analysis device.

RELATED APPLICATION

The present application is a Continuation-In-Part of U.S. patentapplication Ser. No. 11/974,260, filed Oct. 12, 2007 now U.S. Pat. No.7,663,754, and titled FLUID FLOW VISUALIZATION AND ANALYSIS, and havingthe same inventors as the present patent application. U.S. patentapplication Ser. No. 11/974,260 is hereby incorporated by reference inits entirety for any purpose.

GOVERNMENT SUPPORT

This invention was made with government support from the NationalScience Foundation (NSF) under NSF Grant No. IIP-0740550. The UnitedStates Government has certain rights in this invention.

TECHNICAL FIELD

This document pertains generally to fluid flow analysis, and moreparticularly, but not by way of limitation, to device, methods andsystems for demonstrating and teaching of fluid flow phenomena.

BACKGROUND

Fluid Dynamics is the study of fluid flow and can be difficult toconceptualize without laboratory experiments. Particle Image Velocimetry(PIV) is used to visualize and analyze fluid flow but particle imagevelocimetry systems that are used for research are expensive and utilizeClass IV Nd:YAG lasers that may be dangerous, if appropriate safetymeasures are not followed, and cost prohibitive for educationalpurposes. Examples of particle image velocimetry systems are describedin U.S. Pat. Nos. 6,013,921; 6,549,274; 6,700,652; and 6,940,888.

OVERVIEW

A fluid flow analysis system can include a computational unit to performcomputational fluid dynamics, a particle image velocimetry device togenerate physical test data, and a control unit in communication withthe computational unit to receive computational fluid dynamics data andin communication with the particle image velocity device to receive thephysical test data. In an embodiment, the computational unit receivesboundary conditions related to a fluid flow path in the particle imagevelocimetry device. In an embodiment, the computational unit downloadsboundary conditions from a server. In an embodiment, the computationalunit downloads boundary conditions from a user. In an embodiment, thecomputational unit downloads boundary conditions that relate to walls ofthe fluid flow path. In an embodiment, the computational unit generatesmesh data for a given flow model to be modeled in the particle imagevelocimetry device. In an embodiment, the computational unit computesinitial flow conditions based on prior data from the particle imagevelocimetry device. In an embodiment, the computational unit is part ofthe control unit.

The particle image velocimetry device can include a housing; a fluidflow path operably connected to the housing; a pump connected to thehousing and to move fluid in the fluid flow path; a removable obstacleassembly that includes a portion of the fluid flow path and an obstaclepositioned in the portion of the fluid flow path; a light source toilluminate fluid adjacent the obstacle in the fluid flow path; an imagerto image fluid adjacent the obstacle in the fluid flow path; a furthercontrol unit in communication with the imager, or combinations thereof.In an embodiment, the further control unit is to receive commandsincluding at least one of the group consisting of brightness, exposure,frame rate, gain, and video size. In an embodiment, the imager is adigital, charge coupled device, wherein the housing includes a bloodflow simulation device operably connected to the fluid flow path. In anembodiment, the housing includes a pressure measurement device tomeasure fluid pressure in the fluid flow path. In an embodiment. thefluid flow path travels adjacent the light source to cool the lightsource. In an embodiment, the pump runs continuously while the system ison and provides fluid flow to cool the light source. In an embodiment,the obstacle is removable from the body such that a further obstacle maybe positioned in the body such that a different obstacle may be studiedin the particle image velocimetry device. In an embodiment, the lightsource includes a laser that emits a low power, green light. In anembodiment, the housing includes a slot to receive the obstacleassembly, wherein the slot includes an open end that is not aligned withthe light source such that no direct light escapes the housing with theobstacle assembly removed, and wherein the light source includes aswitch that turns off the light source with the obstacle assemblyremoved and that turns on the light source with the obstacle assembly inthe slot.

A method can include providing computational fluid flow dynamics data ofa fluid flow model; performing particle image velocimetry on the fluidflow model; and comparing particle image velocimetry data to thecomputational fluid flow dynamics data. In an embodiment, the methodfurther includes a user uploading at least one of boundary conditions orinitial conditions for performing computational fluid flow dynamicsanalysis. In an embodiment, the method further includes downloadingstored boundary conditions and initial conditions for computationalfluid flow dynamics analysis.

In an example, a control system for a particle image velocimetry deviceis provided that includes a input/output to communicate with a fluidflow device; a data storage to store fluid flow data; an imager controlmodule to remotely control operation of an imager in the fluid flowdevice; and a display module to output data acquired from the fluid flowdevice. In an example, the imager control device is to control at leastone of brightness, exposure, frame rate, gain, and video size. In anexample, the input/output includes a key that allows operation of thefluid flow device that can not operate absent the key. In an example,the input/output is to allow a plurality of users to access a singlefluid flow device. In an example, an analysis module is provided toanalyze particle image velocimetry data. In an example, methods ofoperating the present devices and systems are described. A particleimage velocimetry method, includes flowing particle entrained fluid in afluid flow path past an obstacle; illuminating the fluid at theobstacle; imaging fluid flow at the obstacle; optionally replacing theobstacle with a further obstacle while automatically turning off theillumination. In an example, replacing the obstacle includes continuingto flow fluid in the fluid flow path to cool the light source whilereplacing the obstacle. In an example, imaging fluid flow includesremotely controlling imaging and sending image data to a remotelocation. In an example, imaging includes remote display of the imagedata.

This overview is intended to provide an overview of the subject matterof the present patent application. Each of the above examples and theremainder of the present disclosure can be combined with any otherexample or disclosure herein. It is not intended to provide an exclusiveor exhaustive explanation of the invention. The detailed description isincluded to provide further information about the subject matter of thepresent patent application.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsmay describe substantially similar components in different views. Likenumerals having different letter suffixes may represent differentinstances of substantially similar components. The drawings illustrategenerally, by way of example, but not by way of limitation, variousembodiments discussed in the present document.

FIG. 1 is a schematic view of fluid flow analysis system.

FIG. 2 is a view of a fluid flow analysis device.

FIG. 3 is a view of a fluid flow analysis device.

FIG. 4 is a view of a fluid flow analysis device.

FIG. 5 is an enlarged, partial view of a fluid flow analysis device.

FIG. 6 is a partial view of a flow model assembly.

FIG. 7 is a schematic view of a fluid flow path according to anembodiment.

FIG. 8A is a view of a flow obstacle insert according to an embodiment.

FIG. 8B is a view of a flow obstacle insert according to an embodiment.

FIG. 8C is a view of a flow obstacle insert according to an embodiment.

FIG. 8D is a view of a flow obstacle insert according to an embodiment.

FIG. 8E is a view of a flow obstacle insert according to an embodiment.

FIG. 9 is a view of a control unit.

FIG. 10 is a view of a graphical user interface.

FIG. 11 is a display of data acquired according to an embodiment of thepresent invention.

FIGS. 12A and 12B are schematic views of an application of the presentsystem.

FIG. 13 is a schematic view of an application of the present system.

FIGS. 14A-14D are schematic views of an application of the presentsystem.

FIG. 15 is a view of a further embodiment of the flow model assembly.

FIG. 16 is a schematic view of a computational, visualization, andanalysis system according to an embodiment of the present invention.

FIG. 17 is a flow chart of a method according to an embodiment.

FIG. 18 is a flow phenomena diagram according to an embodiment.

FIGS. 19-20 are example images produced by embodiment(s).

FIG. 21 is an example computational fluid dynamic, speed flow shadedplot.

DETAILED DESCRIPTION

The following detailed description includes references to theaccompanying drawings, which form a part of the detailed description.The drawings show, by way of illustration, specific embodiments in whichthe invention may be practiced. These embodiments, which are alsoreferred to herein as “examples,” are described in enough detail toenable those skilled in the art to practice the invention. Theembodiments may be combined, other embodiments may be utilized, orstructural, logical and electrical changes may be made without departingfrom the scope of the present invention. The following detaileddescription is, therefore, not to be taken in a limiting sense, and thescope of the present invention is defined by the appended claims andtheir equivalents.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one. In this document, the term“or” is used to refer to a nonexclusive or, such that “A or B” includes“A but not B,” “B but not A,” and “A and B,” unless otherwise indicated.Furthermore, all publications, patents, and patent documents referred toin this document are incorporated by reference herein in their entirety,as though individually incorporated by reference. In the event ofinconsistent usages between this document and those documents soincorporated by reference, the usage in the incorporated reference(s)should be considered supplementary to that of this document; forirreconcilable inconsistencies, the usage in this document controls.Similar elements in different views may be indicated using the samereference numbers from different views to aid in the understanding ofthe present disclosure.

FIG. 1 shows a fluid flow analysis, e.g., a particle image velocimetry,system 100 that includes a fluid flow device 110, such as a particleimage velocimetry device, connected to a network 115. The particle imagevelocimetry device 100 is adapted to take images of a fluid as it passesan imaging field. Based on images, the flow speed and direction of thefluid is determined at different parts of the field. In one use, thesystem fluid flow analysis 100 is used in an educational setting toteach students the principals of fluid flow. The present system 100 isparticularly suited for such a setting as research level particle imagevelocimetry devices are too expensive, difficult to use, or pose dangersto the students that may be unfamiliar with a research level system. Thenetwork 115 connects the device 110 to a control unit 120. The network115 can be a global computer network, such as the internet. In a furtherexample, the network 115 is an intranet or other local area network.Control unit 120 includes rule sets to control operation of the device110. A user 124 may directly interface with the control unit 120, forexample with an input device such as a keyboard, mouse, other pointingdevice, etc. A remote user or users 124 may connect to the control unit120 through the network 115. The control unit 120 can include a remoteserver and data storage. The control unit 120 can further includealgorithms to analyze data from the device 110. Control unit 120 canfurther include a display to display the data in a raw form or ananalyzed form. Control unit 120 can further form an automaticallyconfigured wireless network to which users within a certain distance(e.g. inside a building/lab) may connect, e.g., via wi-fi or Bluetoothenabled devices such as notebook computers and personal data assistants.In an example, the control unit 120 is a personal computer that includesa processor, memory and a web browser to enable communication with thefluid flow device 110.

System 100 includes a computational unit 130 to provide computationalfluid dynamics (CFD) ability to the present system 100. Computationalunit 130 can be a general purpose computer that includes an operatingsystem and specific CFD software run by the operating system. Unit 130may further include additional hardware that enhances CFD, such asarithmetic logic units, parallel processor, etc. Unit 130 can furtherinclude various computer networking devices that allow it to communicatevia the network 115 to the control unit 120 and, if needed, to remoteusers 126. In a further embodiment, the computational unit is asub-system of control unit 120. The computational unit 130 is to usenumerical methods to simulate and predict various flow properties undermodel and initial conditions. Such models and conditions can includelaminar flow and two-dimension modeling. Further discussion of CFD andoperation of computation unit 130 is found below.

System 100 can further include an interactive fluid flow server 140,which can provide control software for the fluid flow device 110 to thecontrol unit 120, provide communication links between the control unit120, remote users 126, if any, and the computational unit 130. Server140 can also provide data files for computational unit 130.

In operation, the fluid flow device 110 takes images of fluid flow,e.g., with entrained particles, based on control signals from thecontrol unit 120. These images are sent to the control unit 120 via adirect link, e.g., a firewire cable, or via network 115. The controlunit 120 analyzes the image data to provide a fluid flow data. This datamay be presented as a visual representation or as raw data. Raw data caninclude numerical data. The visual representation can play an importantrole in teaching fluid dynamics to students. The user 124 or 126 maychange certain operational parameters of the fluid flow device 110 toimprove the capture of data or alter the flow being analyzed.

FIG. 2 shows a schematic view of a fluid flow device 110 according to anembodiment. The device 110 includes a housing 203 to support a pump 205,a fluid reservoir 207, and an obstacle insert 210. The housing enclosesall of these elements in an embodiment of the present invention. A fluidflow path 212 fluidly connects the pump 205, reservoir 207, and obstacleinsert assembly 210. The fluid flow path 212 is mostly enclosed withinthe housing 203. In an embodiment a relatively short portion of thefluid flow path can extend outside the housing 203. In an embodiment,the fluid in the path is water. A light source 220 is positioned in thehousing and illuminates the fluid flow path 212 at the obstacle insertassembly 210 such that the fluid and any entrained particles arevisible. An imager 225 is positioned in the housing and images the fluidat the obstacle insert assembly. In an embodiment, the imager 225 takespictures of the fluid covering the areas before, at, and after theobstacle insert assembly. The obstacle insert assembly 210 is adapted tochange the obstacle in the fluid flow path at the field where the lightsource 220 illuminates the fluid and the imager 225 can image theilluminated fluid at this field. A power source 230 provides electricalpower to the pump 205, light source 220, and the imager 225. The powersource 230 can include a battery or circuitry to receive standardutility power and output a DC power signal. In an embodiment, the powersource 230 outputs different power signals to the pump, light source,and imager. For example, the pump 205 may require a power signal ofabout 12 volts and 2 amps (max.). The light source may require a powersignal of 3 volts and 0.3 amp (max.). An input/output (“I/O”) 235 isconnected to housing 203. The I/O 235 is serial connection, modem,firewire, i.e., IEEE 1394, wireless, IEEE 802.016 connection, or othersuch connection to a further electronic device such as network 115 orcontrol unit 120 as shown in FIG. 1. The I/O 235 can input controlsignals to at least one of the light source 220, imager 225, and pump205. The I/O 235 can also output the image data from the imager to thecontrol unit, e.g., control unit 120 as shown in FIG. 1. The I/O 235 canfurther include a key and keyhole, i.e., a mechanical key system, or beadapted to receive an electronic key to enable or disable the fluid flowdevice 110.

In an option, a control unit 240 is positioned in the housing 203. Thiscontrol unit 240 can be in communication with at least the imager and,if desired, with the pump 205 and light source 220, to set defaultoperational parameters of at least one of these devices. The controlunit 240 may further include memory to store data from the imager 225.The control unit 240 can further control operation of the input/output235.

FIG. 3 shows an external view of an embodiment of the fluid flowanalysis device 110. Device 110 includes a box-like housing 301 with aconnected lid 303 to create a closed internal space to hold theoperating parts therein. The housing 301 is formed of a rigid, opaquematerial, such as metal or plastic. The front face 305 of housing 301includes an indicator light 307 to show whether the device 110 is on oroff, i.e., powered or unpowered. A fluid flow control knob 309 extendsfrom the front face 305. This knob 309 operates a fluid flow variablevalve, which is fluidly connected to a fluid flow path, to increase anddecrease the speed of fluid flow in the fluid flow path within thedevice. In a further embodiment, an electro-mechanical actuator, notshown, is provided with the housing to control fluid flow in place ofthe manual fluid flow valve. Such an actuator would be controlled bycontrol signals from the control unit to control the fluid flow rate.The flow model assembly 310 is received in a slot in the front face 305of housing 301. The slot includes an open end in the housing. The openend is not aligned with the light source such that no direct lightescapes the housing with the obstacle assembly removed. Assembly 310 canbe releasably held in the fully inserted position by ball and detentmechanism or by magnets. The fluid flow path further extends out of thefront face 305 via elbow connectors 313, transparent tubing 315 andreleasable connectors 317. The releasable connectors 317 are fluid tightwhen removed from mating connectors of the flow model assembly 310.These releasable connectors 317 allow for the removal of the flow modelassembly 310 with the device 101 powered in the on state. The connectors317 are released and the flow model assembly 310 is removed from thehousing 301 such the obstacle insert in the flow model assembly can bechanged.

The lid 303 includes apertures such that the fluid flow path extendsoutside the lid. A large aperture 321 is provided above a fluidreservoir that is within the housing. A reservoir cover 323 is visiblethrough the aperture 321 and can be removed without removing the lid 303such that additional fluid can be added to the reservoir withoutstopping the device 101. Lid 303 is fixed to the open top of the housing301 such that access to the parts therein is not easily attained.However, access to the flow model assembly and the fluid is easilyattained. This allows a relatively inexperienced user to use the devicewith a reduced chance the user will damage the device or injurethemselves.

FIG. 4 shows a view of fluid flow analysis device 110, which includespump 205, reservoir 207, obstacle insert 210, for example, fluid flowmodel 310, light source 220, imager 225, and power source 230. Aninput/output is not shown. Moreover, fixed portions of the fluid flowpath, including the elbows 313 and connectors 317, are shown. The fluidflow path will be described in greater detail elsewhere in thisdocument. The pump 205 includes an inlet 411 and an outlet 413. Inlet411 is in fluid communication with the fluid reservoir 207. Outlet 413exits pressurized fluid from pump 205. That is the pump creates apressure head in the fluid at the outlet, which causes the fluid to flowin the path. A damping system 415 connects the pump 205 to the box 301.The damping system 415 includes at least one and, in an embodiment, aplurality of structures to reduce the vibration and noise caused by thepump. Such vibration may alter the results of the fluid flow analysis.The vibration reduction structures can include a polymer spacer blockintermediate a wall of the box and the pump. A plurality of rigid,vibration damping washers are staked intermediate a plurality of soft,polymer O-rings to further dampen vibrations from the pump to thehousing wall of the box. A plastic bolt and nut are used to fix the pumpto the sidewall of the housing. In an embodiment, O-rings are positionedon the interior and exterior of the sidewall. Washers are positionedoutwardly of the O-rings. A damping jacket may wrap around the outersurface of the pump to further dampen vibrations and reduce noise. Apump will have a certain level of vibration due to its pumping action.The damping system will reduce the level of vibration so as to notinterfere with the fluid flow analysis. The damping system will alsoreduce pump noise.

As vibration may adversely effect the operation of the particle imagevelocimetry device, its housing 301 can include vibration damping feet.The feet can be rubberized feet in an example. The feet may also assistin noise reduction.

The fluid flow obstacle insert assembly 210 includes a base 431 tosupport an intermediate member 433 that defines a portion of the fluidflow path, and a cover 435. The intermediate member 433 is transparentto the light from the light source such that the light illuminates thefluid flow path in the intermediate member. The intermediate member 435includes two fluid ports at a front face. The ports extend outwardly ofa front face of the housing when the insert assembly 210 is positionedin the housing. A face plate 439 is fixed to the front of the stack ofthe base 431, intermediate member 433, and cover 435. The face platecovers the aperture in the front wall of the housing to assist inpreventing light from escaping the housing. In an embodiment, the portsfix the face plate to the intermediate member. The cover 435 isremovably secured to the top of the intermediate member. Removal of thecover 435 gives access to the obstacle insert. The cover 435 fluidlyseals the fluid flow path in the intermediate member 433. An aperture437 that acts as a viewing window for the portion of the fluid flow pathin the intermediate member is positioned in the cover 435. In anembodiment, the aperture 437 is aligned with the portion of the fluidflow path that includes the obstacle insert.

The light source 220 is fixed adjacent one sidewall of housing 301. Thelight source 220 includes an emitter 421 to output light toward thefluid flow insert 310. The emitter 421 can be a light emitting diode inan example. The emitter can be a laser in an embodiment. In anembodiment, the light emitted by the light source is a green light. Inan embodiment, the light emitted is a red light. The laser can be acategory II, line laser that emits light at about 532 nm. Whileillustrated as a single light source, it will be recognized that afurther light source can be mounted in the housing. The only requirementof the light source is that it illuminate particles in the fluid and bevisible to the imager. In an embodiment, the light source emits greenlight or red light or a combination thereof. In an embodiment, thefurther light source could be mounted orthogonal to the light source220. This will reduce edge effects at the flow model insert. The emitter421 is mounted to a block 423. In an embodiment, thermal paste isapplied at the interface between the emitter and the mounting block. Themounting block 423 is fixed to the housing and includes a portion of thefluid flow path through the block or mounted to the block. The mountingblock can include an elongate support that is fixed to a main body ofthe block via a damper, such as an o-ring, to dampen effects of shockduring movement of the fluid flow device to thus protect the lightsource from damage. As a result, the fluid flow will cool the block 423,which in turn will cool the emitter 421 to assist in operation of theemitter and prolong its life.

An electrical junction 440 is fixed to the housing 301. The electricaljunction 440 electrically connects the electrical components of thedevice 110 together. The junction 440 is connected to power source 230and distributes power to at least the pump 205 and light source 220. Theelectrical junction may power the imager 225 as well. In anotherexample, the imager is powered through its communication connection, forexample, through a universal serial bus (USB) or firewire connection.The junction 440 may further act as a communication junction between theimager and a remote terminal, such as the control unit 120.

The imager 225 includes a mount 450 and the imager device (not shown inFIG. 4). The mount 450 includes a plurality of support posts 452 thatare fixed to the housing lid. In an embodiment, the posts arecantilevered from the housing lid. These support posts extend inwardlyinto the interior of the housing aligned with the aperture 437 of theobstacle insert assembly 210. A support platform or board, such as aprinted circuit board (PCB), 454 is fixed to the ends of the supportposts 452. Platform 454 can act as support for an imaging chip. Animaging device, such as a charge coupled device, is fixed to the bottomof the platform 454. The lens of the imaging device is aligned andclosely adjacent the aperture 437 such that the imaging device canreceive reflected light from the fluid flow path at the obstacle insert.

The imaging device is a high resolution, black and white camera in anembodiment. In a further example, the imaging device is a color camera.The camera can be a digital camera. The camera can include chargecoupled devices. The imaging device may further provide raster scanning.The color camera may be used to study a fluid mixing of fluids that havedifferent colors. For example, a first unit of water colored with afirst dye and a second unit of water colored with a second dye can beimaged by the color imager at the imaging area. In a further example,the imager can image two different fluids that may have different flowproperties and different colors. The imager may be adapted to sense andoutput pseudo-color image data that can be enhanced or manipulated inthe control unit or locally with the device 110 to produce a colorpresentation of the fluid flow.

A switch 470 is positioned at the rearward end of the flow modelassembly 310. The switch 470 is in an “on” position with the flow modelassembly 310 fully inserted into the slot in the housing 301. The switch470 in the “on” position allows power to the light source 220 and fullpower to the pump 205. When the flow model assembly 310 is slidoutwardly of the housing, then the switch 470 moves to its default,“off” position. The switch 470 in the “off” position turns off the powerto the light source. The switch in the “off” position turns off the fullpower connection and allows for a reduced power to the pump. The pumpwill continue to move fluid through the fluid flow path in this reducedpower state but at a reduced pressure or reduced volume. In oneembodiment, the pump will continue to move fluid to cool the lightsource even with the light source off.

FIG. 5 shows an enlarged perspective, partial view of the fluid flowdevice 110. In this view, the imager 225 is shown with the lower part ofthe support posts 452 and the support platform 454. On the bottom sideof the platform 454 is the imaging device 550, which includes a lenssystem focused on a portion of the fluid flow path 555 that is directlybelow the aperture 437 and in which is positioned a fluid flow obstacle800. Details of the fluid flow obstacle 800 will be described in greaterdetail with regard to FIGS. 8A-8E. A connector unit 560 includes a bolt561 extending through the base 431, intermediate member 433, and cover437 and a fastener, such as a wing nut, 563 to removable hold the base431, intermediate member 433, and cover 437 together. The base 431 andintermediate member 433 include a translucent portion and may besupported by a rigid backing, for example, a metal plate. The rigidbacking ensures that the seal, e.g., o-ring or gasket, that seals thefluid flow path in the obstacle insert assembly 210 has an even,fluid-tight seal. The obstacle insert 800 sits in a recess in theintermediate member 433 such that the base portion 805 is not in thefluid flow path 570 and the obstacle 810 is in the fluid flow path. Therecess in the intermediate member 433 has a depth essentially equal tothe height of the base of the obstacle insert 800. The flow model bolt561 and slot on the bottom of the housing 301 act as a guide to the flowmodel assembly 310. The bolt head is slightly larger than the slot widthwhich allows the flow model assembly 310 to glide into the slot butprevent it from lifting up, which securely locates the flow modelassembly 310 in the slot.

FIG. 6 shows an enlarged, partial view of the obstacle insert 210 withthe cover 435 removed from the intermediate member 433 to show the fluidflow path 570 and obstacle insert 800 therein. The bottom surface of thefluid flow path is essentially co-planar including the top surface ofthe obstacle insert base 805. The smooth-walled, gradually turned fluidflow path in the obstacle insert 210 allows the fluid flow to developgradually and to be relatively uniform before the obstacle 800 isencountered. The fluid flow in one of the ports (not shown) and travelspast the obstacle insert 800, which creates a fluid flow pattern basedon the type and shape of obstacle 810. The imager 225 takes an image ofthe fluid at the obstacle 810 for purposes of education and study offluid flow dynamics in an embodiment.

The housing, insert, imager position, and flow path are all selected tominimize the effect of gravity on the particles in the fluid flow path.This corrects for one source of error in the study of fluid flowdynamics when using system 100. For example and with reference to FIGS.4-6 the gravitational effects will be in the z-axis. The imager istaking images of the fluid flow with the path in the x-y plane, thus thegravitational effect is minimized. The fluid flow can be analyzed usingparticle image velocimetry techniques. The fluid is seeded withparticles. The particles are selected to have minimum impact on fluidflow and maximize the contrast with the background and fluid. Ideallythe particles will have essentially a neutral buoyancy relative to thefluid in the flow path.

FIG. 7 shows a schematic view of the fluid flow path 701 within thedevice 110. Path 701 includes a plurality of tubing sections, at leastsome of which is transparent such that some indirect illumination of thefluid is visible, for example, outside the housing to indicate to a userthat the light source is working. This also allows visual inspection ofpotential bubbles in the system and helps in removing them via thesyringe. A plurality of fluid connectors join the tubing sections. Theconnectors may be opaque. While not drawn to scale, the tubing lengthsas shown represent lengths relative to other lengths of tubing.Beginning at the pump 205, an outlet 705 connects to tubing 707 thatinputs into a tee-connector 709. One leg 711 of the tee 709 connectsthrough tubing 711 to the light source 220. The fluid flowing in thispath will cool the light source 220. An outlet 713 of light source 220connects to tee-connector 715. A leg of t-connector 715 connects totubing 717 that outlets outside a top of the housing and entersreservoir 207. Reservoir 207 is in fluid communication with a furtherport that connects to tubing 719 that connects to an elbow 721. A leg723 of tee-connector 725 is fluidly connected to the elbow 721. A leg727 of tee-connector 725 connects to the pump 205. The precedingrepresents a cooling fluid flow path. A feed-back path is also provided.The feed-back path includes a second leg 731 of tee connector 709 thatfluidly connects with tee-connector 733. A leg 735 of tee-connector 733fluidly connects with a flow reducer 737 that connects with a reduceddiameter tube 739. At the other end of the tube 739 is a reducer 741that fluidly connects with a leg 743 of tee-connector 725 to completethe fluid circuit. The reduced diameter tube 739 and reducers 737, 741restrict the volume of fluid flow through the feed-back path. If theobstacle assembly is removed, then the fluid can still flow through thefeed-back path with the pump at a reduced power setting.

Faster flow allows fluid streamline visualization, which is veryimportant in understanding fluid flow phenomena. Slow flow allowsparticle image velocimetry analysis to be performed allowing thecalculation of velocity and direction of the fluid flow. Once fluidvelocity is calculated other flow parameters such as voracity, shearstress, shear strain can be calculated. Such visualization andcalculation can be performed in the control unit 120 or in the remoteuser locations 126.

The fluid flow imaging portion 760 of the fluid flow path 701 is nowdescribed. A further leg 761 of tee-connector 733 fluidly connects to anelbow 763, which in turn fluidly connects to a variable flow resistor,e.g., a variable valve, 765 controlled by manual knob 309. The user canincrease/decrease fluid flow by activation of knob 309, which in turnopens and closes the fluid flow path at flow resistor 765. Flow resistor765 fluidly connects to a port 313 and an exterior tube 315. Tube 315connects to port 317, that connects to the portion of fluid flow path inthe obstacle insert assembly 210. A further port 317 exits the assembly210 at the front of the housing and fluidly connects to a tube 315. Asecond port 313 connects to tube 315 and reenters the housing. A furthertubing 771 connects to leg 773 through an elbow 775 and tube 777.

The fluid typically flows in the direction shown and described above. Ifit is desired to reverse fluid flow, then one of the connections to thereservoir 207 is released. The fluid flow automatically reversesdirection based on the connections shown and need to continuallycirculate fluid to cool the light source. The fluid flow may also bereversed by insertion of a valve to block fluid flow. In an example,such a valve may be placed in tube that is closely adjacent thereservoir, such as tube 717, 719 or in place of connector 721. Otherpositions of such a valve are within the scope of the presentdisclosure.

The fluid flow path is configured to allow fluid to flow even with thereservoir 205 removed from the fluid flow path. The reservoir 205, maybe removed from the path when further fluid is added to the reservoir orseed particles are added to the reservoir, for example. Such continuousfluid flow cools the light source and does not require the pump to beturned off when the reservoir is accessed by the user.

Fluid flow measurement devices 791, 793 are optionally connected to theat least one and preferably separate portions of the fluid flow path. Inan embodiment, at least one fluid flow measurement device 791 or 793 isfluidly connected to a tubing outside the housing. The FIG. 7illustrated embodiment shows the measurement device 791 in tubing 315 onthe right and the measurement device 793 in separate tubing 315 on theleft. As a result, one of the fluid flow measurement device 791, 793 ison the inlet side of the obstacle insert 210 and the other is on theoutlet side of the obstacle insert. It will be recognized that eithermeasurement device can be placed elsewhere in the fluid flow path. Themeasurement devices 791, 793 can be pressure transducers to measure thefluid pressure at the location in the fluid flow path. For example, inthe illustrated example, the devices 791, 793 can measure the pressuredifferential across the obstacle insert 210 at a certain flow rate. Thedevices 791, 793 can further include flow rate sensors to determine flowrate. As a result, the pressure drop across the obstacle insert at ameasured flow rate can be measured. In operation, a user can measure thepressure and flow rate absent an obstacle in the insert 210. An obstacleis then placed in the insert 210 and a second measurement is taken. Fromthis the pressure drop due to the obstacle can be calculated, i.e., thedifference between the no-obstacle measurement and the obstaclemeasurement. The measurement devices 791, 793 can further be connectedto the I/O of the fluid flow device 110 such that the data measured canbe stored or sent to the remote users and control unit. Thus, this datacan be correlated to the fluid flow image data taken by the imager.

The fluid flow path and the elements that define the fluid flow path areadapted to fluidly confine and allow the flow of different types ofliquids. Accordingly, different types of liquid can be analyzed andstudied. In an example, different transparent fluids with differentviscosities can be used to study different Reynolds numbers, e.g.,inertial forces/viscous forces. Such study can teach students thedifference between laminar flow and turbulent flow.

FIGS. 8A-8E show various embodiments of a fluid flow obstacle insert800. The description of the common features of insert is shown in FIGS.8A-8E with use reference numbers absent any alphabetic suffix.Discussions of individual insert with use an alphabetic suffix thatcorresponds to the figure. Insert 800 includes a base 805 that supportsa shaped obstacle 810 upstanding from an upper surface of the base 805.Base 805 is shaped generally like a rectangular prism with a volume thatis only slightly smaller than the recess in the base of obstacleassembly. Other shapes are also within the scope of the presentdisclosure such as equilateral shapes, e.g., equilateral triangularprisms. The base 805 includes a height such that it is essentiallyco-planar with the lower surface of the fluid flow path in the obstacleassembly. This results in the base having little effect on the fluidflow in the fluid flow path. The base 805 may further indicate the fieldof view of the imager so that the user will know the intended view. Theobstacle 810 on the other hand extends outwardly, as shown upwardly,from the base 805. The obstacle 810 is intended to be directly in theflow path with the base 805 inserted in the recess of the obstacleassembly base. The obstacle 810 will cause the fluid in the fluid flowpath to alter course and as a result cause fluid to demonstrate variousimportant aspects of flow phenomena, such as rotational flow, flowseparation, turbulence, flow interaction with boundaries, etc. The useof different obstacles will thus be a learning tool for a studentstudying various fluid flow phenomena. The base 805 being equilateralresults in the obstacle 810 being placed with any side toward theincoming flow. Non-equilateral obstacles can also be used with variousembodiments of the present invention. The obstacles can be of any shapeof interest to demonstrate fluid flow phenomena. The obstacles canfurther be mounted such that they move on the base in response to fluidflow. In an example, the obstacle is a pinwheel or waterwheel shape thatwill rotate as the fluid flows past the obstacle. In a further example,the resistance to rotation can be adjusted. For example, a nut could betightened on a bolt that secured the movable obstacle on the base. Thus,the user can adjust the freedom of movement of the obstacle. Theorientation of the obstacle can also be changed and the bolt can befully tightened making the obstacle immovable at a fixed orientation.Accordingly, each of the obstacles 800 of FIGS. 8A-8E can provide fourdifferent flow obstacles based on their orientation in the recess. Forexample, the obstacle 810A of FIG. 8A has a three dimensional shape witha triangular cross section. The hypotenuse side surface can face theinflow of fluid such that the user can view, sample, and study theaffects of fluid flow striking this surface and flowing around a vertexside and a short flat side with the long flat side facing the outflow offluid. The entire obstacle 800A can be turned such that the short flatside faces the inflow of fluid by simply removing the insert assembly,opening the assembly, lifting the insert, rotating the insert, replacingthe insert, closing the assembly, and reinserting the assembly into thefluid flow device. In general, the number of different fluid flowparadigms each inert 800 represents is determined by the number of sidesof the base 805.

The inserts can be transparent (for example made from acrylic or otherclear polymer) allowing light to pass through the obstruction andilluminate the fluid on the other side of the obstruction. This willallow student user to observe fluid flow all around an obstacle, such asa complete cylinder, aerofoil or other obstacle shapes. Depending on thenumber and position of light sources, some orientations may bepreferable (obstacle may block the light source to some of the particlesdepending on orientation, or in the case of transparent obstacles, maybend the light and may potentially produce artifacts in the image). Theinserts are designed in a way such that at least one orientation willminimize such effects. The translucent parts in the flow model assemblyare reinforced with metal plates to ensure an even seal on an o-ring inthe flow model assembly, in an embodiment. These plates also ensurerobustness of the flow model assembly and create a good seal, otherwiseuniform pressure is not applied and the fluid may leak

Each of the obstacles 805B-805E will now be discussed.

Obstacle 805B includes base 805, which is the same for all obstacles sothat the base fits the recess in the intermediate member of the obstacleassembly 210. The obstacle 810B includes an upstanding solid geometricstructure with three straight, flat and planar sides, a fourth concavelycurved side surface. The top surface is flat to mate and possiblyfluidly seal against the cover 435 of obstacle assembly 210.

Obstacle 805C includes base 805 and an obstacle 810C that includes threeflat, planar sides (with two the same length and the third significantlyshorter). A fourth side opposite the short side is convex.

Obstacle 805D includes base 805 and a rectangular prism obstacle 805D.None of the sides of the prism are the same length.

Obstacle 805E is a triangular prism that is offset from toward theleftward side of its base 805E with one leg 831 of the triangle beinglonger than the others 832, 833. Leg 832 is positioned adjacent one sideof the base 805E. The vertex of sides 831, 833 is positioned at aboutthe center of base 805E.

Other obstacles can also be used. These other obstacles can place aflexible plate in the fluid flow path. Such a plate can be moved on thefluid flow. The plate may further be cantilevered such that one end offree to move based on the forces of the fluid flow. Other obstacles cansimulate airplane wings or hydrofoils. Still other obstacles cansimulate a nozzle, a throat, or a diffuser. The flow separationphenomena can be studied very well with the present system 1000 by usingvarious flow models and by varying the speed of the flow the separationeffects can be observed visually. The flow models, i.e., inserts withobstacles, can model a nozzle, a throat, or a diffuser. The obstacleportion of the insert would follow the shape of the top and bottom edgeof the diagram shown in FIG. 18. The flow phenomena that we can observecan be summarized in the diagram shown in FIG. 18. It will be recognizedthat the insert need not include each of these different flowstructures. The boundary layers, velocity, and pressure gradients foreach of these flow structures can be studied, imaged, visualized, andcalculated. See for example, “Mechanics of Fluids,” B. S. Massey,Chapman & Hall, ISN 0 412 34280 4 and “Fluid Mechanics,” Frank M. White,McGraw-Hill Book Company, ISBN 0 07 069673X, hereby incorporated byreference.

Flow separation occurs because of excessive momentum loss in theboundary layer near a wall. This loss can be initiated by an adversepressure gradient where dp/dx>O. Flow separation can occur in a diffuseror a sudden expansion. In the diffuser flow separation will occur at oneor both walls if the diffuser angle is too large leading to excessiveadverse pressure gradient. Flow separation will result in reverse flow,increased losses and poor pressure recovery. This is called a diffuserstall. In a favorable pressure gradient—like in a nozzle—where dp/dx<Oflow separation can never occur. Separation occurs when δu/δy=0 (orτ_(w)=O) where τ_(w) is the wall shear stress. The boundary layer maybecome turbulent once the laminar layer separates. Separation streamlineis the line of zero velocity dividing the forward and reverse flow, andit starts from the separation point. The reverse flow causes largeirregular eddies. These eddies are undesirable because of energy loss.The separated boundary layer curls, and the disturbed flow regioncontinues downstream. The imager can clearly image these effects andprovide the data to multiple users as described herein. The pressuredownstream remains approximately the same as at the separation pointbecause the energy is dissipated as heat.

Both laminar and turbulent boundary layers separate, but laminar layerstend to separate more easily. This is because the laminar flow velocitygradient from the wall is lower and the adverse pressure gradient canmore rapidly halt the slow moving fluid near the wall, e.g., the wall ofthe fluid flow path or tubes described herein. A turbulent boundarylayer is more resistant to adverse pressure gradient. However, greaterthe adverse pressure gradient quicker the separation for both laminarand turbulent flows. The boundary layer, δ(x), thickens rapidly in anadverse pressure gradient, and one can no longer assume that δ(x) issmall. The boundary layer separation greatly affects the flow as awhole. A wake of disturbed flow downstream is formed which radicallyalters the flow pattern. Such a wake can be imaged and displayed tousers according to the teachings herein. The effective boundary of theflow is an unknown shape—which also includes the zone ofseparation—instead of the wall. The altered flow pattern may cause theposition of the minimum pressure to move upstream. This may result inthe point of separation moving upstream. Flow separation becomes veryimportant in the design of aerodynamics. For example, flow separationincreases drag in racing cars or airplanes. The present system canfurther image flow separation caused by sharp edges that can be studiedby the user.

Still other obstacles can include variously shaped recesses in theobstacle insert. Examples of recesses include any upstanding shapedescribed herein, but recessed into the upper surface of the obstaclebody.

FIG. 9 is a view of a control unit 120 remote from the fluid analysisdevice 110. The control unit is to receive data from the device 110 andinstructions from the users. This data can be transmitted wirelessly orover a wired network. At times using this received data andinstructions, the control unit sends control signals to the fluid flowanalysis device 110. The control unit 120 can be a server withappropriate storage and rule sets. The control unit 120 depicted in FIG.9 includes an input/output module 910 that provides communicationbetween modules in the unit 120 and outside devices, such ascommunication over networks to the fluid flow device 110. In particular,the I/O module 910 is adapted to receive image data from the imager. TheI/O module 910 may further include data transfer devices such as auniversal serial bus, serial bus, disk drives, or further globalcomputer connections such as the Internet. The I/O module 910 mayfurther include a network interface device is to provide connectivitybetween the control unit to a network using any suitable communicationsprotocol. Examples of communications protocols include wirelessprotocols such as Institute of Electrical and Electronics Engineers(IEEE) 802.11a/b/g/h and IEEE 802.16., Ethernet IEEE 802.3x, TCP/IP, andthe like. The network can be the Internet, an intranet, a local areanetwork (LAN), a wide area network (WAN), and a cellular network basedon GSM and TDMA, as examples. It will be recognized that the I/O modulemay connect to one type of network or any number of networks of the sameor different types. If a standard network is used, it will further berecognized that the I/O module may further utilize network browsers suchas Internet Explorer, Mozilla, Opera, etc. and may use a standardoperating system such as GNU/Linux, MS-Windows, or Mac-OS. The I/O 910may further provide a digital key to the fluid flow device I/O 235 toallow operation of the fluid flow device 110. The I/O module 910 isfurther adapted to provide communication with a plurality of users. Agroup of users may be using the same fluid flow device. This will behelpful for group projects and labs in undergraduate coursework. A groupof users may each individually be using separate fluid flow devicesusing a same control unit. This will allow a central control unit tocontrol a plurality of fluid flow devices to centralize programming andprovide improved updating and troubleshooting of the control unit. Thiscan also allow a professor to stage example of principals of fluiddynamics being studied and show the students actual, an possiblyreal-time, fluid flow examples, whether or not the students are remote.

Control unit 120 further includes data storage 920 to store raw datafrom the fluid flow device, to store control parameters at the time ofproducing the raw data, and to store analyzed data that has beenprocessed according to fluid flow dynamics. An analysis module 930 isprovided to apply the analysis rule sets to the data stored in the datastorage 920. The analysis module can perform particle image velocimetryanalysis. The module may further operate and the data to add color tothe images generated by the data. A default rule set 935 is stored inthe control unit 120. The default rule set 935 includes the base controlparameters for control of the fluid flow device 110 and the login inrequirements for users, such as students, to access the control unit andhence the fluid flow device 110.

An imager control module 940 is provided to control the imager in thefluid flow device. The imager control module 940 will store theparameters for the particular imager in the fluid flow device 110. Theimager control module 940 will further allow the users to change certainparameters to improve the results of the fluid flow analysis. Examplesof such parameters are brightness, exposure, gain, etc.

The control unit 120 further includes a display module 950. The displaymodule 950 can present the images and videos from the fluid flow devicein essentially real-time such that a data collection period can beginafter the user can see that the system 100 is working and good data canbe acquired. Further, the display module 950 can provide a user friendlyand familiar interface between the hardware and software of the system100 and a novice user. This will aid in use of the present system as ateaching tool. The display module 950 and other modules can be used viaa user friendly interface, such as a web browser.

The above modules may reside in a single computer, or can be distributedacross multiple computers connected via a network or a bus. A pluralityof user interfaces or front-end servers may receive requests andcommunicate with appropriate modules, and forward back their replies.Front-end servers may connect to plurality of controllers which then canbe connected to plurality of devices. A plurality of analysis servers orstorage servers may also be used.

Fluid flow device and the controller device may be merged. Thecontroller device may be embedded within the body of the fluid flowdevice and connected to the camera internally.

FIG. 10 is a view of a graphical user interface 1000 that may be usedwith the control unit. The graphical user interface (GUI) 1000 providesdisplay of graphics including symbols, interactive buttons or fields,data displays and other representations to a user. GUI 1000 can beremote from the fluid flow device and communicate to the elements of thefluid flow device through a communication channel, e.g. as describedherein. GUI 1000 provides a user friendly device to allow the user tocontrol operation of the fluid flow device and acquire fluid flow data.GUI 1000 includes an imager control 1010 and a fluid flow data preview1030. Imager control 1010 includes a plurality of control settings 1011for the imager. These control settings 1011 include by way of example,but are not limited to, brightness 1012, exposure 1013, gain 1014,frames 1015, and video size 1016. Brightness 1012 controls the overallbrightness of the image acquired by the imager. In an embodiment,brightness is set to a medium-high value for visualization (i.e, for apreview image), and to a medium-low value for actual data acquisition inparticle image velocimetry. In some setups, artifacts such as smallbubbles stuck to various surfaces may be present. To correct for suchartifacts, the seed particles are chosen to be brighter than theartifacts. The user can use the present GUI 1000 to lower brightness(and adjust gain and exposure) to a point where the seed particlesimaged brighter than the artifacts such that the remaining artifacts arenot imaged or the not outside general data errors. Generally, for PIV,it is desirable to have bright particles with high contrast from thebackground. Ideally, everything other than the particle seeds are asdark as possible. Exposure 1013 controls the time the image sensors aregoing to be exposed per frame. If this value is high, sensors are goingto be exposed longer, resulting in longer streamline effects as theparticle seeds being imaged are moving. For PIV analysis, exposure is aslow as possible to obtain a fast snapshot of the particle seeds aspoints rather than streamlines. However, when exposure is low, fewerphotons hit the image sensors in the duration allocated per frame (i.e.,exposed to photons), so the particle seeds will appear dimmer. One wayto compensate for the dimmer particle seed images is to increase thegain. Gain 1014 controls how sensitive the image sensors are per unittime. Increasing gain amplifies the image data. However, increasing gainalso increases the noise in the signal, and hence in the data. Frames1015 controls the number of frames that will be captured in anindividual data acquisition session. It is desirable to keep this valuelow when adjusting the settings for fast response, and set this value toa higher value when the settings are satisfactory. Video size 1016controls the scaling factor for the purpose of generating a video image.For fast experimentation, it may be preferable to reduce the size to 50%or 25% and increase it when the optimal parameters are found. This is tocontrol the size of the visible image, such as that shown in the preview1030. The acquired PIV data need not be affected by this setting as thedata is always available full-size. Smaller video image sizes are usefulto reduce latency experienced by users during heavy network trafficperiods or with users having low bandwidth connections

The settings 1011 can further include user manipulatable fields 1021,1022, 1023, which allow that user to change the settings. As shown, eachof the control settings 1012-1016 each includes three fields. However,three fields may not be required for an individual setting or additionalfields may be required. Changing the number of fields for an individualsetting is within the scope of the present disclosure. As shown in FIG.10, there is a decrease field 1021, a value field 1022 and an increasefields 1023. As these input fields can be replicated for each controlsetting 1012-1016, only one will be described in detail for clarity ofdescription. The value field 1022 shows the current value for therespective control setting, as shown in FIG. 10 brightness. On one sideof field 1022 is a decrease field 1021. On the other side of field 1022is an increase field 1023. When the user selects the decrease field thenthe value of that setting, which is shown in field 1022, is decreased.When the user selects the increase field then the value of that setting,which is shown in field 1022, is increased. The fields 1021 and 1023 canbe graphical buttons that are highlighted when selected, i.e., pressedusing an input device such as a mouse or other pointing device, andchange the value of the respective control setting by one. The fields1021 and 1023 may further be continually selected to rapidly change thevalue of the respective setting. Value field 1022 can show the absolutevalue of the setting. In an alternative, the value field 1022 shows thepercent of the maximum (i.e. 0-100) for any given setting. This can makethe system easier for a student or other novice to control the imagerwithout learning the specifics and absolute values of settings such asbrightness, exposure, gain, frames, video size, etc. The remote user orthe fluid flow device translates the percent settings into appropriatesetting values that the imager can understand. In the embodiment with aplurality of users, each of the users is shown the current value of thesettings in field 1022 shown on their respective remote user terminal.In an application, only one user may change the settings. In anotherapplication, each of the users can change the settings. This allows theusers to collaborate and possibly teach each other how changing thesettings can affect the fluid flow data that is being acquired.

The fluid flow data preview 1030 is a display field that shows the imagedata being acquired by the imager is shown to the user. The preview 1030includes a video presentation of the image data. The preview can besample of the image data. The preview can change when the imagingcontrol settings 1012-1016 are changed. This graphic of the image databeing shown to the user provides the user with an essentially real-timeview of fluid flow in the fluid flow device at the obstacle. The usercan change the settings of the imager to improve the data quality.

The GUI 1000 further includes navigation links 1040 that allow a user tonavigate to different graphical user interfaces or other modules of afluid flow visualization/data acquisition program. These links caninclude, but are not limited to acquire data and analyze data. Otherlinks can include end, log off, link to other materials related to thisfield of study, link to class/lab websites, link to website associatedwith the present system for support or tutorials. Other links can beprovided.

FIG. 11 is a visual representation of data 1100 acquired using thesystem 100 described herein. The data can be displayed on a displaydevice such as a computer monitor or other electronic display. Thevisual representation as shown in FIG. 11 is a vector field overlaid ona frame of data. The vector field is one presentation of data computedfrom the raw image data acquired by the fluid flow device. Other datacan be computed from the experimental data acquired using the fluid flowdevice and the controls. Computed data can be calculated and graphicallypresented to a user. Examples of such data include streamline, voracity,shear stress, shear strain, turbulence intensity, etc. Computation canbe performed in the analysis module 930 of the control unit 120 (FIG.9).

The operation of the system 100 will now be described. In an example,user must install the software or logon to the control unit 120 to usethe fluid flow device 110. A user's own computer can be connected to thefluid flow device 110 and the software installed from a storage media ordownloaded over a network. The software will detect the various hardwareand device software and install the proper fluid flow system software.In an example, the user needs to merely point their web browser to thename of IP address of the server on which the software is loaded or theDNS name of the machine acting as the server. Thus, no software needs toreside on the user's computer, which allows the user's computer to becompliant with the server and use of the present invention generallyindependent of the user's computer hardware or software. Software of thepresent invention is then only needed for the server and the users'computers only need functional web browser and network connectionsoftware, which is readily available in most notebooks/computers.

Fluid flow device 110 can now be set up for an experiment. The window437 in the fluid flow model insert 310 is cleaned as a unclear windowwill result in poor data. The obstacle insert is selected and placed inthe recess of the intermediate member 433 of the insert 310. The cover435 is positioned over the intermediate member 433 and fluidly sealsthis portion of the fluid flow path. The insert is then slid into theslot in the front of the housing 301. When fully inserted, the insert210 or 310 is releasably held in the housing slot and activates theswitch to allow the light source 220 to be powered and the pump 205 tobe fully powered. Connectors fluidly connect the insert to fluid flowpath, for example, the tubing that is exterior to the housing as shownin FIGS. 3 and 7. The reservoir can then be filled with a fluid. In anexample, the fluid is water. The fluid is then seeded with particlesthat will be visible when illuminated by the light source but will notimpact the fluid flow. The seed particles can range in size from 1micron to about 100 microns depending on the density of the transparentworking fluid and Stokes number. The seed particles can be made fromnylon, polyimid, polystyrene, among others. In an example, the particlesare polyimid for density matching with the flow medium. The particlescan be coated particles to maximize the reflected light. Particles canalso be fluorescent. The particles are placed in the fluid filledreservoir.

The fluid flow device can be connected to the control device at anytime. The fluid flow device can now be powered on. The light source andthe pump will start as the switch is on. The associated control softwareor methods should be started at the control unit 120. Images of the flowshould now be displayed at the control unit. A user at the fluid flowdevice can now manually slow the fluid flow or speed the fluid flow byadjusting the knob that controls the fluid flow resistance. In oneembodiment, the flow speed can be controlled using an electronic valveconnected to and controlled by the control unit 120. In this embodiment,the flow speed can be manually adjusted at valve 309.

When beginning a new experiment, there may be air bubbles in the fluidflow path. One method for removing air bubbles is squeezing andreleasing the tubing external to the housing. This moves the bubbleswithin the fluid flow path and possibly moves any bubbles to thereservoir. If the bubbles persist, then a syringe can be connected toone of the connections and used to gently move the bubbles.Alternatively, the syringe can be used to add fluid that can move theair bubbles along without turning off the device 110. In use, thesyringe can pull liquid and the bubbles out of the flow path. The gasthat forms the bubbles and the liquid are separated in the syringe.Thereafter, the liquid is injected back into the fluid flow path.Cleaning the surface of the window 437 also reduces the chances of airbubbles sticking to the window which can restrict the optical path tothe imager. Transparent or semi-transparent tubing help identifying andalleviating bubble related issues faster and easier.

The flow model insert 210 or 310 can be changed with the device 110 inoperation. The fluid flow path is disconnected from the insert 210 or310. The fluid will continue to flow to cool the light source. Theinsert is removed from the slot in the housing. The electrical controlswitch moves to the “off” position that places the pump in a reducedpower mode and turns the light source off. The obstacle 800 can now bechanged in the insert assembly.

The imager is controlled remotely by the control unit 120 to acquiredata from the fluid flow device 110. The user can control manyparameters of the imagers as described herein. The acquired data canthen be analyzed and used remotely from the device 110. The control unit110 provides a networked imager control with essentially real-timevisualization of the image data such that the user can adjust at leastthe imager parameters to achieve the best results. The control unit canconnect to the fluid flow device through any electronic network usingany operating system via a web browser.

The control unit can export the acquired data or analyze the data for auser. The data can be exported in a plurality of formats for additionalanalysis using other software. Examples of these formats include text,png plots, post script, piv files compatible with GPIV, an open sourceparticle image analysis program.

FIGS. 12A and 12B show a schematic view of an application 1200 of thepresent system 100 for use to provide a visual learning, teaching orexperimental tool for fluid pressure versus fluid flow. In someembodiments of the present invention seed particles are not required.One such embodiment is illustrated in FIGS. 12A and 12B. Each of FIGS.12A and 12B schematically show a portion of a flow path 1205. This fluidflow path portion could be any portion of the fluid flow path of thefluid flow device described herein. In one embodiment, the fluid flowpath portion shown in FIGS. 12A and 12B is positioned at the locationwhere the image can acquire image data. FIG. 12A shows an applicationwhere the fluid flow path is vertical. FIG. 12B shows an applicationwhere the fluid flow path is horizontal. Each of FIGS. 12A and 12Bincludes a thin flexible plate 1210 within the flow path 1205. In anembodiment, the plate 1210 is connected to an obstacle insert to beplaced in the fluid flow obstacle assembly and placed in the field ofview of the imager. The fluid flows in the direction of arrows 1215A and1215B, respectively. Referring now to FIG. 12A, the fluid flow impingeson the surface of the plate 1210, which surface faces the inflow of thefluid. As a result the fluid deflects the plate 1210 upwardly away fromthe inflow such that the fluid can flow past the plate. The movement ofthe plate 1210 is shown in broken line in FIG. 12A. Referring now toFIG. 12B the plate 1210 is positioned loosely adjacent one side of thepath 1205. It will be recognized that the distance from the side of thepath is exaggerated for purposes of illustration. The flow of fluid1215B past the plate 1210 may force the plate away from the sidewall andout into the fluid flow as shown by the broken line in FIG. 12B. As thefluid velocity increases, the plate 1210 will be deflected more becauseof the higher pressure. However, the FIG. 12B embodiment may beself-limiting. These embodiments can provide a further visualization offluid dynamics for teaching and understanding of the complex forces inthis field of study.

FIG. 13 shows a system 1300 to simulate blood flow in the present system100. System 1300 includes a motor 1305 to drive a cam 1310 into periodiccontact with a flexible portion 1315 of the fluid flow path. Thisportion of the fluid flow path 1315 can be a flexible, transparentsilicon tube to simulate a vein or artery. The motor 1305, cam 1310 andfluid flow portion 1315 are positioned with the housing, e.g., 301. Themotor 1305 could be controlled to drive the cam 1310 into contact withfluid flow path portion 1315 to simulate a heart beat. The fluid flowpath is flexible and resilient such that the cam 1310 deflects a portionof the path, which in turn springs back to its normal size when the cam1310 moves from contacting the path 1315. In another example, the cam1310 is shaped such that its revolution movement creates the heart beatfluid flow in the fluid flow path. In one aspect, the motor and cam arepositioned away from the obstacle insert assembly such that the obstacleinsert used could represent blockages in a persons circulatory system.The present application is not limited to people, the motor and camcould be controlled or selected to mimic other animals.

In a further embodiment, the pump 205 is configured to output fluid flowthat mimics a heartbeat. The pump can produce pulsating fluid flow atvarious frequencies; some of which can closely mimic a heartbeat. Afluid that more closely mimics blood viscosity can also be used. Oneexample is a medium sucrose solution as the fluid. Some of the seedingcan be sized to represent cells, such as red or white blood cellsa.

FIG. 14A show a schematic illustration of a pressure measurement system1400 that includes fluid flow insert assembly 1410 with luers 1415connected thereto. The luers 1415 fluidly connects via fluid connections1417, such as vias or tubes, to a pressure gauge 1420. The illustratedembodiment includes three luers with three respective fluid connections.It is within the scope of an embodiment of the present invention toinclude a single luer 1415 and fluid connection 1417. In anotherembodiment, any plurality of luers 1415 and connections 1417 areprovided. The flow assembly 1410 is similar to the assembly describedelsewhere in the present documents unless otherwise noted.

FIG. 14B is a top, partial view of the portion of the fluid flow insertassembly 1400 that receives an obstacle 1425. The obstacle 1425 is shownin broken line to indicate that it is removable from the recess 1428 inthe bottom plate 1430 of the assembly 1400. A plurality of channels 1430are formed in the assembly extending vertically downwardly from the topof the assembly 1400, i.e., vertical channel 1431, and then extendinghorizontally under the bottom surface of the recess 1428, i.e.,horizontal channel 1432. An end portion 1433 of the horizontal channel1432 is open to apertures 1435 at an edge of an obstacle insert 1425.Referring now to FIG. 14C, a top view of the obstacle insert 1425 foruse with the pressure measurement system 1400. The obstacle insert 1425includes a body 805 and an obstacle 810, which can be essentially thesame as described herein but for the apertures 1435 in an edge of thebody 805. These apertures will allow the pressure in the fluid totransmit from the fluid flow path through apertures 1435, to channels1431, 1432, through luers 1415 and fluid connections 1417 to a pressuresensors 1420. The pressure sensor is mounted outside the housing of thesystem 110. In an embodiment, the pressure sensor 1420 records thepressure readings and sends same via an I/O connection to remote users.

The illustrated embodiments shown in FIGS. 14A-14C further show that thepairs of apertures 1435 and channels 1430 are positioned with one pairbefore the obstacle 810, one pair at obstacle 810, and one pair afterthe obstacle 810. This allows the pressure differences resulting from aspecific obstacle insert to be measured at three different locations.Based on these values, Bernoulli's equation can then be calculated.

FIG. 14D shows an other embodiment of the insert 1400 including at leasttwo connectors 1450 that are connected to fluid apertures that areadjacent the obstacle. These fluid obstacle can be the same as thosedescribed above with regard to FIGS. 14A-14C. The connectors 1450 andfluidly connected apertures are positioned to one side of the aperture437 such that they do not obstruct the field of view of the imager (notshown in FIG. 14D). A portable pressure sensor (not shown) can beconnected to the connectors 1450 and be positioned external to thehousing. In another embodiment, the pressure sensor records the readingsand sends same via the I/O to the remote users and the control unit.

FIG. 15 shows a schematic view of the fluid flow device 1500 being usedto for teaching mixing flow phenomena. A portion 1510 of the fluid flowpath is outside the housing 301 and includes an injection point 1515.The injection point can be a Tee junction or syringe accepting point. Inuse, the reservoir would not be completely filled as further liquid willbe injected during experimentation. In an example, the reservoir isabout ½ to ¾ full. At the injection point 1515 a liquid 1517, preferablydifferent than the liquid 1518 already flowing in the fluid flow path,is injected. Both liquids 1517 and 1518 would flow into the insert 210wherein the imager would record the flow of the two liquids past theimaging site. While described as two liquids, any plurality of liquidscan be used. In an example, water is flowing in the fluid flow path. Ahigher density liquid, such as oil, is injected. In a laminar flow, thetwo liquids would not mix. Moreover, seed particles can be placed ineach liquid and imaged past an obstacle as well to determine mixingeffects of the obstacle. Other examples could include injection of soapinto water.

The present system 100 is ideal for the educational environment asindustrial or research particle image velocimetry (PIV) systems typicalcost round $100,000. Moreover, there are safety considerations as theseindustrial PIV systems use high power lasers, such as class IV lasers.The cost and potentially dangerous components prohibit the use of suchsystems for educational purposes. The present inventors recognized thesedrawbacks of the industrial PIV systems and the need for hands onexperiments to learn fluid flow dynamics. To achieve some of thesegoals, the present housing encloses all powered parts yet providesvisual evidence of the device in an operational state by allowing somediffuse, indirect light from the light source to leak from the housingor by images from the imager.

The present system can further record data that is later used inqualitative and quantitative analysis, for example, in the control unitor at remote user locations. The flow of a real fluid is very complexand, as a result, complete solution of problems can seldom be obtainedwithout recourse to experiment. The present system provides the vehiclefor such experiments without the need for expensive or dangerousequipment. Fluid mechanics is a highly visual subject. While using thepresent system the user(s) can learn about the flow qualitatively andquantitatively using particle image velocimetry (PIV). The most commonmathematical method for flow visualization is the streamline pattern.All visualizations can be computed at the control unit and/or the remoteuser for display. Flow patterns can be described by lines and there areseveral types of lines. See for example, “Mechanics of Fluids,” B. S.Massey, Chapman & Hall, ISN 0 412 34280 4 and “Fluid Mechanics,” FrankM. White, McGraw-Hill Book Company, ISBN 0 07 069673X, herebyincorporated by reference. First, Streamline: this is an imaginary curveacross which—at that instant—no fluid is flowing. It can also be calleda flowline or line of flow. At this instant in time the direction of thevelocity of every single particle on this line is along this line. Thepattern, which several streamlines form, gives a very good descriptionof the flow. Since the streamlines are describing an instant of time thepatterns they form can be considered to be an instantaneous photographof the flow. The present system shows these visualizations of flow whenimages of the particles moving fast through the flow model are taken.Second, Pathline: An individual particle in the flow does notnecessarily follow the flow. So the actual path that a given fluidparticle follows is called a Pathline. If one considers a streamline asan instantaneous photograph of the flow, a pathline is time exposure ofthe path of the particle at successive instants of time. Third,Streakline: This line is the locus of particles which have passedthrough a prescribed point. Another term used for this line is filamentline. Traditionally a streakline can be produced experimentally by thecontinuous release of marked particles such as dye, smoke or bubbles. Inthe present system streaklines are produced using solid particles whichare illuminated by a light source, such as a laser or light emittingdiode. FIGS. 19-20 are two examples of images produced by the presentsystem.

The present system can further provide a basis for the hands on study offlow in ducts. There is no general analysis of fluid motion. The reasonfor this is that very complex changes occur in fluid behavior atmoderate Reynolds Numbers. At this introductory level Reynolds number isconsidered to be the primary parameter affecting transition from laminarto turbulent flow.

${Re} = \frac{\rho\;{VL}}{\mu}$Where V is the average stream velocity, p is the fluid density, p is thefluid dynamic viscosity, and L is the characteristic length. In anexample operation of the present system water is used as the liquid. At20° C., the density and dynamic viscosity for water are 998 kg/m3 and1.003×10⁻³ Ns/m², respectively. In non circular ducts, as used in anembodiment of the present system, hydraulic diameter can be used for L.Hydraulic Diameter=(4×Area)/Wetted PerimeterThe value of Hydraulic diameter in an embodiment of the present systemis constant. With the dimensions of the fluid flow path in the presentsystem being 5 mm×25 mm, the hydraulic diameter is 8.33. As a result,the following approximate ranges occur for flow in the fluid flow path:0<Re<1: highly viscous laminar, “creeping” motion.1<Re<10²: laminar, strong Reynolds number dependence10²<Re<10³: laminar, boundary layer theory useful10³<Re<10⁴: transition to turbulence10⁴<Re<10⁶: turbulent, moderate Reynolds number dependence10⁶<Re<∞: turbulent, slight Reynolds number dependenceThese values of Reynolds number a good indication of the flow regimes,but the values can vary with surface roughness, flow geometry, and inletflow stream fluctuations. The flow in the present system is consideredto be internal flow because the fluid is constrained by the boundingwalls. The viscous boundary layers grow downstream of the entrance tothe portion of the fluid flow path. This results in the retardation ofthe axial flow at the wall and acceleration of the center fluid so thatthe incompressible continuity law is satisfied.

In the present system, the users will be able to study flow not only instraight ducts but also flow over obstructions by inserting various flowmodel obstacles. One flow model studies the effect of reduction in flowarea on the flow. The effect can be explained by considering theBernoulli's equation:P/ρg+u ²/2g+z=ConstantWhere, P is pressure and z is height. Bernoulli's equation only appliesto frictionless (inviscid), steady and constant density flows.Bernoulli's relation is generally true only for a single streamline. Thepresent system can image fluid flow in a horizontal plane and hencethere is no significant gravitational effect on the flow. As a result, zcan be eliminated from the Bernoulli's equation. If we consider the flowin a converging duct, continuity tells us that as the area gets smallerthe flow speed increases. See for example, “Mechanics of Fluids,” B. S.Massey, Chapman & Hall, ISN 0 412 34280 4 and “Fluid Mechanics,” FrankM. White, McGraw-Hill Book Company, ISBN 0 07 069673X, herebyincorporated by reference. Also Bernoulli's equation tells us that asthe speed increases pressure must decrease. The present system can usethe computing power and systems to generate this type of data for auser.

FIG. 16 shows a schematic of an application 1600 of the presentinvention, specifically, design of a fluid flow model 1610,computational fluid dynamic analysis engine 1620, and particle imagevelocimetry 1630. Such an application 1600 can be used in an educationalsetting or in preliminary proof of concept in an industrial setting toreduce costs. Design 1610 can include initial ideas regarding a fluidflow model, such as those described herein, which can include specificexamples of fluid flow obstacles shown in FIGS. 8A-8E. For theseprovided fluid flow models, a model file can be created and stored at aremote server, e.g., server 140 in FIG. 1. In other embodiments, a usercreated flow model design may be created at 1610. This user createddesign is then uploaded as a numerical representation to the CFDanalysis engine 1620. CFD analysis engine 1620 then analyzing this databased on initial conditions and assumptions regarding the design model.In certain cases, an assumption is made that the flow is laminar and twodimensional grids are used of computation. Other assumptions and initialconditions are with the scope of the present invention. Moreover, whenusing the presently described fluid flow system 110, certain boundariesand flow conditions are known and can be fixed in the CFD analysisengine 1620. Examples of the boundaries include the walls of fluid flowpathway in the fluid flow model. A mesh representation of the fluid flowmodel is created. Various options are available here, but for purposesof education, a two-dimensional mesh is used. The finer the mesh, themore data points are produced and, hence, results in more intensive andexpensive computation. It may be desirable to perform multipleiterations on a design to efficiently develop a computational model ofthe fluid flow model. Other data needed for CFD is the initialvelocities of the fluid at various points when the fluid enters thefluid flow model. This data can be generated from data files of previousfluid flow analysis in system 110, i.e., prior PIV runs. The CFD engine1620 produces data tables, graphs, or other representations of the fluidflow model. The fluid flow model can then be revised based on theseresults. The CFD engine 1620 can thus minimize the number of physicaltests that needs to be performed during the validation process of adesign. This reduces the cost of development as physical prototypes andtests (e.g., PIV) are more expensive then the computational effort. TheCFD engine 1620 can produce graphics that illustrate the computationalresults that can be compared to the physical data. An example of a CFDspeed flow shaded plot is shown in FIG. 21.

After computational optimization of design is achieved, then a physicaltest (e.g., PIV) can be performed. A user could compare thecomputational results to the PIV test results, e.g., the immediatelyabove graph versus previously graphs shown herein. If the results do notagree with the CFD analysis, then the design process 1600 repeats itselfuntil an optimized working design is achieved.

Once satisfied that fluid flow model meets a criteria, then the physicalfluid flow model can be used in the presently described system 110 togenerate PIV data, 1630. After the PIV data is generated, the user cancompare the physical results, e.g., the PIV data, with the computationaldata from CFD engine 1620. A user can then investigate any differencesbetween theoretical data (CFD) and the physical data (PIV). The processcan be performed again to achieve the desired results or to comparechanges to a design.

FIG. 17 shows a flow chart of a fluid flow analysis method 1700according to an embodiment of the present invention. At 1705, a flowmodel is selected. At 1708, a determination is made whether the model isan existing, known model. If so, then the method 1700 loads flow modeldata at 1709 and then moves to perform CFD at 1715. Loading the flowmodel data 1709 can include retrieving the data from the server of asupport system for the present invention or the user can manually loadthe data. If not at 1708, then at 1710 a determination is made whetherCFD was previously performed. If not, then CFD is performed at 1715. Ifso, then the method 1700 moves to performing PIV using the systemdescribed herein, 1720. At 1725, the physical experimental from the PIVflow model system is then compared to the computational data from theCFD step 1715. If the physical data does not match the CFD data, thenthe user may return to perform PIV 1720. Otherwise the method ends.

The loading of flow model data, 1709, can include the user uploadingtheir own model if they are working with a custom one. The user canfurther select various options pertaining grid generation, which is usedin CFD. For existing models, a number of grids may already be generated.Otherwise, the user enters boundary conditions manually. In an alternateembodiment, the boundary conditions are determined from previous PIVdata.

Performing CFD, 1715, can include producing graphs and images (e.g.velocity vector field, velocity magnitude graphs) that are equivalent tographs and images that are produced by PIV using the present system.

Comparing PIV results with the corresponding CFD results, 1725, caninclude comparing the raw data, graphs, images, or combinations thereof.The user should be able to explain how well they match, or if they donot match, try to explain why it did not match. Based on thiscomparison, the user should be able to go back and reiterate to moreclosely match the data or see how changes to the PIV test equipment ordata input into the CFD step may change results.

The present system(s) and method(s) should assist a user in analysis ofexperiments, including but not limited to, quantitatively generate avelocity vector field, plot data in graphical format with label andunits of variables, e.g. shaded plot, extract data from the results andplot in linear graphical form, e.g. velocity versus location, calculatethe average flow rate at a particular cross section, understandvariability in experimental results, export velocity data into Excel oranother analysis software to perform further calculations, e.g.calculate vorticity.

The present system(s) and method(s) should assist a user inunderstanding fluids concepts, such as laminar flow, turbulent flow,Reynolds number, boundary layer, shear layer, strain rates, shear rate,streamlines, vorticity, viscosity, flow separation, continuity,recirculation, flow acceleration and deceleration. When multiple flowmodels are supplied with the fluid flow device, the user will also beassisted in understanding the various flow phenomena observed in theflow models supplied with the system, how to design custom flow modelsto create custom case studies, how to follow the design optimizationprocess (FIG. 16), research skills including using a professionallaboratory notebook, the importance of keeping accurate records, readingthe manual and following operating instructions, changing the seedingdensity incrementally and observing the PIV results, following thesequential process of removing bubbles—if any—as per the instructionmanual, recording PIV data for further analysis and report writing,ability to vary the flow rate and direction, ability to interchange theflow models, and a use of present software and hardware, and optimizingPIV parameters.

The above Detailed Description is intended to be illustrative, and notrestrictive. Accordingly, the various embodiments described herein maybe implemented with software, firmware, or hardware. The variousembodiments are not necessarily mutually exclusive, as some embodimentscan be combined with one or more other embodiments to form newembodiments. For example, the above-described embodiments (and/oraspects thereof) embodiments may be combined, utilized and derivedtherefrom, such that structural and logical substitutions and changesmay be made without departing from the scope of this disclosure. Suchembodiments of the inventive subject matter may be referred to herein,individually and/or collectively, by the term “invention” merely forconvenience and without intending to voluntarily limit the scope of thisapplication to any single invention or inventive concept if more thanone is in fact disclosed. Many other embodiments will be apparent tothose of skill in the art upon reviewing the above description. Thescope of the invention should, therefore, be determined with referenceto the appended claims, along with the full scope of equivalents towhich such claims are entitled.

Other embodiments will be apparent to those of skill in the art uponreviewing the above description. The scope of the invention should,therefore, be determined with reference to the appended claims, alongwith the full scope of equivalents to which such claims are entitled. Inthe appended claims, the terms “including” and “in which” are used asthe plain-English equivalents of the respective terms “comprising” and“wherein.” Also, in the following claims, the terms “including” and“comprising” are open-ended, that is, a system, device, article, orprocess that includes elements in addition to those listed after such aterm in a claim are still deemed to fall within the scope of that claim.Moreover, in the following claims, the terms “first,” “second,” and“third,” etc. are used merely as labels, and are not intended to imposenumerical requirements on their objects.

The Abstract is provided to comply with 37 C.F.R. §1.72(b), whichrequires that it allow the reader to quickly ascertain the nature of thetechnical disclosure. It is submitted with the understanding that itwill not be used to interpret or limit the scope or meaning of theclaims. Also, in the above Detailed Description, various features may begrouped together to streamline the disclosure. This should not beinterpreted as intending that an unclaimed disclosed feature isessential to any claim. Rather, inventive subject matter may lie in lessthan all features of a particular disclosed embodiment. Thus, thefollowing claims are hereby incorporated into the Detailed Description,with each claim standing on its own as a separate embodiment.

1. A fluid flow analysis system, comprising: a computational unit toperform computational fluid dynamics; a particle image velocimetrydevice to generate physical test data at a removable obstacle, whereinthe removable obstacle is positioned in an imaging portion of a fluidflow path; and a control unit in communication with the computationalunit to receive computational fluid dynamics data and in communicationwith the particle image velocity device to receive the physical testdata.
 2. The system of claim 1, wherein the computational unit receivesboundary conditions related to a fluid flow path in the particle imagevelocimetry device.
 3. The system of claim 2, wherein the computationalunit downloads boundary conditions from a server.
 4. The system of claim2, wherein the computational unit downloads boundary conditions from auser.
 5. The system of claim 2, wherein the computational unit downloadsboundary conditions that relate to walls of the fluid flow path.
 6. Thesystem of claim 1, wherein the computational unit generates mesh datafor a given flow model to be modeled in the particle image velocimetrydevice.
 7. The system of claim 1, wherein the computational unitcomputes initial flow conditions based on prior data from the particleimage velocimetry device.
 8. The system of claim 1, wherein thecomputational unit is part of the control unit.
 9. The system of claim1, wherein the fluid flow path travels adjacent a light source, whichilluminates particles in the fluid, to cool the light source, whereinthe control unit controls a pump, wherein the obstacle is removable fromthe imaging portion of a fluid flow path such that a further obstaclemay be positioned in the imaging portion of a fluid flow path such thata different obstacle may be studied in the particle image velocimetrydevice.
 10. A fluid flow analysis system, comprising: a computationalunit to perform computational fluid dynamics; a particle imagevelocimetry device to generate physical test data; and a control unit incommunication with the computational unit to receive computational fluiddynamics data and in communication with the particle image velocitydevice to receive the physical test data; wherein the particle imagevelocimetry device includes: a housing; a fluid flow path operablyconnected to the housing; a pump connected to the housing and to movefluid in the fluid flow path; a removable obstacle assembly thatincludes a portion of the fluid flow path and a removable obstaclepositioned in the portion of the fluid flow path; a light source toilluminate fluid adjacent the obstacle in the fluid flow path; an imagerto image fluid adjacent the obstacle in the fluid flow path; and afurther control unit in communication with the imager.
 11. The system ofclaim 10, wherein the further control unit is to receive commandsincluding at least one of the group consisting of brightness, exposure,frame rate, gain, and video size, wherein the imager is a digital,charge coupled device, wherein the housing includes a blood flowsimulation device operably connected to the fluid flow path, and whereinthe housing includes a pressure measurement device to measure fluidpressure in the fluid flow path.
 12. The system of claim 10, wherein thefluid flow path travels adjacent the light source to cool the lightsource.
 13. The system of claim 12, wherein the pump runs continuouslywhile the system is on and provides fluid flow to cool the light source.14. The system of claim 10, wherein the obstacle is removable from thebody such that a further obstacle may be positioned in the body suchthat a different obstacle may be studied in the particle imagevelocimetry device.
 15. The system of claim 10, wherein the light sourceincludes a laser that emits a low power, green light.
 16. The system ofclaim 10, wherein the housing includes a slot to receive the obstacleassembly, wherein the slot includes an open end that is not aligned withthe light source such that no direct light escapes the housing with theobstacle assembly removed, and wherein the light source includes aswitch that turns off the light source with the obstacle assemblyremoved and that turns on the light source with the obstacle assembly inthe slot.
 17. A fluid flow analysis method, comprising: providingcomputational fluid flow dynamics data of a fluid flow model includinggenerating physical test data at a removable obstacle wherein theremovable obstacle is positioned in an imaging portion of a fluid flowpath; performing particle image velocimetry on the fluid flow model; andcomparing particle image velocimetry data to the computational fluidflow dynamics data.
 18. The method of claim 17, wherein providingcomputational fluid flow dynamics data includes a user uploading atleast one of boundary conditions or initial conditions for performingcomputational fluid flow dynamics analysis.
 19. The method of claim 17,wherein providing computational fluid flow dynamics data includesdownloading stored boundary conditions and initial conditions forcomputational fluid flow dynamics analysis.
 20. The method of claim 17wherein providing computational fluid flow dynamics data includes movingfluid in the fluid flow path adjacent a removable obstacle assembly thatincludes a portion of the fluid flow path and an obstacle positioned inthe portion of the fluid flow path, illuminating fluid adjacent theobstacle in the fluid flow path, and imaging fluid adjacent the obstaclein the fluid flow path.